1. Field of the Invention
This invention relates to a pumping apparatus with a peristaltic drive device for pumping a medium through a line having at least one compressible portion, containing a shaft with cams arranged so as to be offset with respect to one another and with attached lamellae, a positive feed being provided for the lamellae.
2. Description of the Related Art
Pumping apparatuses with a peristaltic drive device for pumping medium through a hose are used, for example, as transfusion pumps and infusion pumps. Appliances of this type are known in the prior art. In most appliances, a return of the lamellae is generated by means of the hose elasticity. In this case, therefore, the hose elasticity must be selected such that it is possible for the lamellae to be pushed back by the hose. Normally, therefore, hoses made from silicone are used. If there is no return system provided, a jamming of the hose and an obstruction of the throughflow or an unwanted backflow may occur.
DE 692 01 966 T2 discloses, for example, the construction of a peristaltic pump for pumping a fluid from a fluid source through a line, a drive shaft being provided, with cam plates which are fastened eccentrically in a helical pattern to the drive shaft along this and can be rotated by means of the latter, and with finger plates which engage on the line and are coupled to the cam plates of the drive shaft. The drive shaft provided is a continuous core shaft, on which the cam plates are fastened. The finger plates each have a passage orifice, with which they are plugged onto the cam plates.
EP 0 422 855 B1 discloses a peristaltic pump with a continuous shaft having cams integrally formed on the latter. The cams have attached to them finger plates which each have an essentially rectangular passage orifice, into which the cams of round cross section engage. The finger plates or fingers press against a diaphragm, under which a hose is led through. The provision of four fingers is preferred in the patent. The individual fingers are of different length or cover a multiple of the distance which another finger covers. A distinction is made between pumping and pinching fingers, the pinching fingers being provided at a first and a third position and the pumping fingers being provided at a second and fourth position. The cams of the pinching fingers are provided on the shaft on one side only, and rotated at 180° with respect to one another, whereas the cams of the pumping fingers are arranged essentially in the same positioning on the shaft.
DE 690 18 208 T2 likewise discloses a peristaltic pump, in which a continuous drive shaft with cams attached to it and with fingers coupled to these is provided. An adjustable orientation means for defining an axis of rotation of the camshaft is provided, in order to linearise the fluid stream through a hose introduced into the linear peristaltic pump. The rotating camshaft is inclined by the adjustable orientation means until the fluid stream is essentially linear. The fingers are of essentially the same length and the cam discs are mounted eccentrically on the drive shaft.
DE 693 03 516 T2 discloses a linear peristaltic pump, in which a motor-operated cam shaft is mounted rotatably in a frame and is arranged parallel to a flexible and likewise mounted hose. The camshaft has at least three cams which are arranged so as to offset at an angle with respect to one another. For each cam, a tappet is provided, which is guided, between guide faces running parallel, in a direction running perpendicularly to the cam shaft and which has end faces for compressing the flexible hose. Each cam is provided with three arcuate portions, a first portion being provided for the pressure phase, a second portion being provided for holding the flexible hose in a closed state, and a third portion being provided for the rapid release of the hose.
A peristaltic pump with a rigid drive shaft is also known from DE 690 10 194 T2. A multiplicity of cams are provided on this drive shaft, too, each of the cams being offset angularly with respect to the in each case adjacent cam. A multiplicity of pressure fingers moving to and fro and cooperating with the cams are provided, these pressure fingers being driven by the cams. The rotational movement of the drive shaft is converted into a linear wave movement of the pressing fingers. A hose is enclosed between the pressure fingers and a pressure plate as an abutment, fluid movement being brought about by the pressure fingers.
DE 690 08 638 T2 discloses a transfusion pump which, via a drive mechanism, moves fingers which, by virtue of their Y-shape and one-sided fastening on one leg, can engage via the other leg on a hose and can compress the latter. The drive mechanism has a drive shaft, on which are attached twelve eccentric cam discs which come to bear against the respective finger extensions. As a result of the rotation of the drive shaft and of the cams located on it, the finger extensions are deflected, thus resulting likewise in the deflection of the legs which are at an angle to these and which bear against the hose, as a consequence of which the latter is compressed continuously and fluid conveyance is brought about.
DE 36 11 643 C2 discloses a peristaltic hose pump which is designed as a push-in unit. The hose pump has twelve first and second pressure elements which act as pressure members and which are arranged one behind the other. The first pressure element is in this case designed as a rectangular plate which has two projections on the side facing the second pressure element. The second pressure element is formed by two bar-shaped identically designed members. Twelve cam discs, against the control face of which a plate bears in each case, are arranged on a drive shaft at uniform intervals somewhat longer than the thickness of the members. Thus, once again, a continuous drive shaft with cam discs attached to it is provided.
DE 25 26 060 A1 discloses a peristaltic hose pump, in which the hose is led through a number of identical connecting rods arranged next to one another and is carried by these and extends through an orifice at one end of each connecting rod, the other end of which is mounted rotatably on a crankpin of a crankshaft bend. The connecting rods are set in an up-and-down movement by the crankshaft. The crankshaft bends are provided, offset at an angle with respect to one another, on the crankshaft. Since the hose is pushed through the connecting rods, it follows the up-and-down movement. The hose is fastened with its ends in a pump end and over its entire length encloses an immoveable circular rod which is centred in the said hose, in so far as no external stress acts on the hose due to the connecting-rod movement. During the progressive transverse wave movement of the hose, the latter comes to bear progressively on the rod, with the result that the ducts located above and below the rod are in each case closed and opened and the movement of fluid in the hose is thereby generated. This takes place without the pinching of the hose, but at a relatively high outlay because of the special shaping of the connecting rods having the lead-through orifices for the hose and because of the additional provision of the rod passing through the hose.
In addition to the abovementioned peristaltic pumps with drive shafts and cams or a crankshaft and bends, it is also known to provide a hose pump having a built-up shaft, as may be gathered, in particular, from DE 92 05 733 U1. The hose pump has slides which are arranged one behind the other and act with their end face in rhythmic alternation upon the hose. The slides are controlled by eccentric discs which are arranged so as to be angularly offset and which rotate about a common axis. The common axis is formed by axle stubs which project in each case on one side of a respective eccentric disc and are inserted into matching depressions of the in each case adjacent eccentric disc. Moreover, for further securing the axle stubs to one another, gudgeons are provided which are inserted in each case into holes of adjacent eccentric discs. The offset of the eccentric discs with respect to one another is formed by the respective offset of holes and gudgeons. This form of construction of a shaft or axle provided with eccentric discs proves to be highly complicated on account of the large number of individual parts which have to be produced so as to fit one another.
DE 298 05 173 U1 discloses a linear diaphragm pump, in which a conveying duct is provided, the shaft being worm-shaped.
U.S. Pat. No. 4,909,710 discloses a pumping apparatus with a one-piece shaft provided on its circumference with cam discs offset with respect to one another. The cam discs are in this case in one piece with the shaft. As a result, as with the cam discs attached to a shaft, it is likewise not possible to have a high throughflow rate in the case of a small type of construction of the pumping apparatus. There is the same restriction as, for example, in the prior art of DE 692 01 966 T2.
DE 32 02 251 C2 discloses an infusion hose pump which has a pumping member with a plurality of peristaltic slides moveable progressively and synchronously in a wavy manner transversely to the pumping zone. These are mounted rotatably at one end on crankpins. The crankpins are mounted eccentrically on a pump axis, so that, during operation, they displace the peristaltic slides to and fro transversely with respect to the pumping zone.